Answer
$(x+1)(x+2)(x+3)=x^{3}+6x^{2}+11x+6$
Work Step by Step
$(x+1)(x+2)(x+3)$
First, evaluate only $(x+1)(x+2)$ and simplify:
$(x+1)(x+2)(x+3)=(x^{2}+2x+x+2)(x+3)=...$
$...=(x^{2}+3x+2)(x+3)=...$
Now, evaluate $(x^{2}+3x+2)(x+3)$ and simplify again:
$...=x^{3}+3x^{2}+3x^{2}+9x+2x+6=...$
$...=x^{3}+6x^{2}+11x+6$